1. Field of the Invention
The present invention relates to a pattern input unit for inputting patterns on a pen touch as in the case of actual handwriting.
2. Description of the Prior Art
FIG. 4 exemplifies a prior art pattern input unit. In the drawing, 1 denotes a tablet as an absolute coordinate data output means, outputting an absolute coordinate data at a pen touch position. A reference numeral 2 denotes a pen touch detector for detecting whether or not a pen (not indicated) is touched to the tablet 1, and a level of an output signal generated therefrom comes on a low level (L) at all times, but when the pen is touched to the tablet 1, it becomes a high level (H). A reference numeral 3 denotes a coordinate converter for converting into a relative coordinate according to an absolute coordinate data generated from the tablet 1. A reference numeral 4 denotes a two-phase clock signal generator for generating a two-phase clock signal. A reference numeral 5 denotes a preset down counter (hereinafter abbreviated as "counter38 ), wherein a relative coordinate data from the coordinate converter 3 is preset, and the clock signal from the two-phase clock signal generator 4 is counted. When the count reads "0", an H single pulse is generated from an output terminal of the counter 5. A reference numeral 6 denotes a J-K flip-flop (J-K FF), wherein a terminal J is connected to a direct current supply through a resistance, a terminal K is connected to a ground, an output signal of the coordinate converter 3 is inputted to a terminal CK, an output signal from the counter 5 is inverted by an inverter 7 and then inputted to a terminal CLR. A reference numeral 8 denotes AND gate, wherein an output signal from the pen touch detector 2 and an output signal from the counter having the level inverted by the inverter 7 are subjected to AND operation, and the output signal is inputted to the coordinate converter 3. Reference numerals 9, 10, 11, 12 denote AND gates each, one two-phase clock signal is inputted to one input terminal of AND gates 9, 11, while the other two-phase clock signal is inputted to one input terminal of AND gates 10, 12, and a signal from a terminal Q of the FF 6 is inputted to the other input terminals of AND gates 9, 10, 11, 12. A reference numeral 13 denotes CPU, to which output signals of AND gates 9, 10, 11, 12 are inputted. A reference 14 denotes a switch with its contact piece connected to CPU 13, a ready access terminal "a" connected to the pen touch detector 2 and a ready access terminal "b" to a ground. A reference numeral 15 denotes a cathode ray tube (CRT), whereon a pattern is displayed by a cathode ray tube control (CRTC) 16 according to the clock signal inputted to CPU 13. A display means is constituted of CRT 15 and CRTC 16.
Next, a pattern input operation will be described with reference to the pattern shown in FIG. 2. (i) First, the pen (not indicated) is touched to an origin on the tablet 1.
Next, when the pen touched to the origin is detached from the tablet 1, an output signal level of the pen touch detector 2 shifts from H to L.
Then, when the pen is touched at a point A on the tablet 1, the output signal level of the pen touch detector 2 shifts from L to H, and an output signal level of AND gate 8, namely an input signal level inputted to the coordinate converter 3 shifts from L to H. Then, it is converted into a relative coordinate (equal to absolute coordinate in this case) of the point A to the origin by the coordinate converter 3 according to a coordinate data of the origin and an absolute coordinate data of the point A, and the relative coordinate is preset on the counter 5. Further, when the relative coordinate is preset on the counter 5, a counting of the clock signal from the two-phase clock signal generator 4 is commenced by the counter 5, and the clock signal from the two-phase clock signal generator 4 is inputted concurrently to CPU 13 by way of AND gates 9 to 12.
Then, when the count reads "0", or counting of the clock signal is over, an H single pulse is generated from the counter 5, and after having the level inverted by the inverter 7, the single pulse is inputted to the terminal CLR of FF 6 and one input terminal of AND gate 8. FF 6 is then cleared, and a level of the terminal Q of FF 6 becomes L. Further, an L single pulse is inputted to the coordinate converter 3 from output terminal of AND gate 8, and the coordinate converter 3 is returned to the state before converting operation.
After that, if the pen is shifted continuously in the direction of point B as touched to the tablet 1, a level of the output terminal of AND gate 8 remains H as the output signal level of the pen touch detector 2 is kept at H and the output terminal level of the counter 5 is also kept at H. Accordingly, a conversion from the absolute coordinate into the relative coordinate is carried out by the coordinate converter 3, the above-described operation is repeated, and a segment on CRT 15 elongates succesively after a move of the pen.
The pen is then stopped moving at the point B and detached from the tablet 1, and from transferring a contact piece of the switch 14 to the ready access terminal "b" from "a", an L signal is inputted to CPU 13, and a segment AB is formed on CRT 15 by CRTC 16 according to the clock signal inputted to CPU 13 by the time when the switch 14 is transferred. (ii) Forming a segment CD continuously
The pen detached from the tablet 1 at the point B is then retouched at point C, and the contact piece of the switch 14 is transferred to the ready access terminal "a" from "b".
Then, from moving the pen toward a point D from the point C, the segment on CRT 15 gets long after a move of the pen as in the case essentially of (i) described above. The pen is then stopped moving at the point D and detached from the tablet 1, and from transferring the contact piece of the switch 14 to the ready access terminal "b" from "a" concurrently, a segment CD is formed on CRT 15. (iii) Forming points F, G, H continuously
The case is similar essentially to the operation of the aforementioned (i), therefore a repeated description will be omitted here.
The prior art pattern input unit is constructed such that the switch 14 is transferred concurrently with detaching the pen from the tablet 1, the pen is retouched to the tablet 1 and then the switch 14 is transferred, accordingly when particularly complicate pattern is inputted, the switch 14 must be operated frequently to troublousness.